WPF listboxitem contextmenu - wpf

Question

I'm trying to create a ContextMenu for a ListBox. It just should be displayed when a ListBoxItem is selected by a right mouse button click. But the ContextMenu opens whenever a right click is done in that ListBox, even when it's empty.
This is my code:
<Window x:Class="WpfApplication4.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow"
Width="525"
Height="350">
<Grid>
<ListBox Name="listIn"
Width="148"
Height="175"
Margin="25,52,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
ItemsSource="{Binding Path=groupid}"
SelectionChanged="listBox1_SelectionChanged"
SelectionMode="Extended" />
<ListBox Name="listOut"
Width="148"
Height="175"
Margin="335,52,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
MouseRightButtonDown="ListBoxItem_MouseRightButtonDown"
SelectedItem="listBox2_SelectionChanged"
SelectionChanged="listBox2_SelectionChanged"
SelectionMode="Extended">
<ListBox.ContextMenu>
<ContextMenu>
<MenuItem Header="update" />
<MenuItem Header="delete" />
</ContextMenu>
</ListBox.ContextMenu>
</ListBox>
<Button Name="cmdRein"
Width="75"
Height="23"
Margin="215,75,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Click="button1_Click"
Content="moveRight" />
<Button Name="cmdRaus"
Width="75"
Height="23"
Margin="217,0,0,145"
HorizontalAlignment="Left"
VerticalAlignment="Bottom"
Click="button2_Click"
Content="moveLeft" />
<Button Name="button1"
Width="59"
Height="23"
Margin="0,14,330,0"
HorizontalAlignment="Right"
VerticalAlignment="Top"
Click="button1_Click_1"
Content="Load" />
<TextBox Name="textBox1"
Width="83"
Height="23"
Margin="25,15,0,0"
HorizontalAlignment="Left"
VerticalAlignment="Top"
TextChanged="textBox1_TextChanged" />
</Grid>

Answer 1

<ListBox>
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}">
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Item 1"/>
<MenuItem Header="Item 2"/>
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Here your Adding ContextMenu for ListBox. This ContextMenu will opens when you right click on the Listbox itself.. If you need the ContextMenu for ListBoxItem alone, initialize ContextMenu for ListBoxItem.

Answer 2

You can define an ItemTemplate for the ListBox like:
<ListBox ItemsSource="{Binding Items, UpdateSourceTrigger=PropertyChanged}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}">
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Item 1"/>
<MenuItem Header="Item 2"/>
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The ItemsSource Item is an ObservableCollection<string>